Reflex sight on a M & P 22 pistol?

[gilfo]

Has anyone mounted a mini reflex sight on the M & P 22 pistol. Not the long gun? Could I just replace the rear sight with a small relex sight?
Just got the M & P and wanted to replace the rear sight, wondering if the extra weight will effect the operation of the slide.
Any input would be greatly appreciated.

Thanks

[Purple]

I put a Burris Fast Fire III on my KelTec PMR 30 (.22M) and the gun cycles just fine. However; I wouldn't trust that the lighter .22LR would be able to cycle the slide correctly with the additional weight.